1. Field of the Invention
The present invention relates generally to implantable prosthesis, and more particularly, to implantable prostheses having particular application for repairing and/or reinforcing an anatomical defect such as a hernia.
2. Background Discussion
Various forms of implantable prostheses have been used for repairing or reinforcing tissue defects, such as soft tissue and muscle wall hernias. For example, it is well known to use an implantable fabric or mesh patch to cover the opening or defect. When an anterior approach is used for the intra-peritoneal ventral hernia repair with a “blind” technique for placing the patch, the patch must be collapsed for passage through the incision and defect, and subsequently released and expanded within the intra-peritoneal space. The patch must then be positioned appropriately, preferably as flat as possible, against the peritoneum. Typically, the side of the patch facing the viscera has tissue barrier characteristics, such as a barrier layer or film. The proper positioning of the patch, however, has proven to be difficult to do through the central access incision in the defect.
More recently, at least one implantable prosthesis is known to include a strap or the like that is secured to a central location of the patch, and extends from the side of the patch that faces the abdominal wall out through the incision to the exterior of the patient's body. This device is described and illustrated in U.S. Pat. No. 7,101,381. The strap provides a means by which to pull on the patch once it is inserted in an effort to secure the patch against the parietal wall, thereby occluding the defect. The strap is either sewn on or otherwise separately secured to the center of the patch, or is constructed in a manner that requires two separate portions to be secured to the patch as shown in FIG. 7 of the publication. Following final placement of the patch, the straps are secured to adjacent fascia or muscle, such as by suturing, with any excess length being trimmed off.
With devices of this type, excess force exerted on the central portion of the patch by the straps can cause the patch to collapse centrally so that the center of the patch begins to pass through the defect, with the radial portion of the patch buckling outwardly (away from the parietal wall) around it. This is extremely undesirable in that buckled or inverted edges expose the unprotected mesh material (portions without a tissue barrier) directly to the internal viscera, increasing the likelihood of undesirable attachments forming between the mesh and the viscera. Further, the securing of the straps to the central portion of the patch may in and of itself compromise the barrier layer. Thus, it is important in any such device to ensure that the patch remains positioned in a uniform plane against the viscera when pulling on the straps to position it.
Although this type of device may incorporate a resilient peripheral “ring” to assist in returning the patch to the desired flat configuration following placement, this ring does not significantly prevent the tendency to buckle as described above. Further, the disclosed ring is comprised of a non-absorbable material, and thus permanently leaves behind a substantial amount of material within the patient. This can be particularly disadvantageous if the ring should ever fracture, which could cause the rough fractured edge(s) to damage surrounding tissue.
Accordingly, it is an object of the present invention to provide improved implantable prostheses for repairing and/or reinforcing soft tissue or muscle wall defects.